Four-Year Data from Phase 2 Trial of Genzyme Gaucher Disease Oral
Compound Suggest Sustained or Continued Improvement Across All Endpoints

Phase 3 Studies of Eliglustat Tartrate Fully Enrolled

CAMBRIDGE, Mass.--(BUSINESS WIRE)--Genzyme,
a Sanofi company (EURONEXT: SAN and NYSE: SNY), announced today
four-year follow-up data from patients enrolled in the phase 2 clinical
trial for its investigational oral therapy for Gaucher disease type 1
known as eliglustat tartrate. Sustained or further improvements were
observed across all endpoints, including markers of bone disease, at the
four-year timepoint. The results will be presented for the first time
this week at the Lysosomal Disease Network WORLD Symposium in San Diego,
Calif.

Eliglustat tartrate, a capsule taken orally, is being developed to
provide a convenient treatment alternative for adult patients with
Gaucher disease type 1, and to offer a broader range of treatment
options for patients and physicians to achieve individual therapeutic
goals. Genzyme’s Cerezyme® (imiglucerase for injection), the
standard of care for patients with Gaucher disease type 1, is
administered through intravenous infusions.

Genzyme previously reported that the 52-week phase 2 trial of eliglustat
tartrate had met its primary composite endpoint: a clinically meaningful
response in at least two of three endpoints (improvements in spleen
size, hemoglobin and platelet levels) in individual patients. Patients
have continued to receive eliglustat tartrate in the extension portion
of the study for over four years. The data from patients on eliglustat
tartrate after four years indicate continued or stabilized improvements
across all endpoints:

Spleen and liver volumes decreased from baseline by a mean of 63
percent and 28 percent respectively.

Hemoglobin and platelet levels had increased from baseline by a mean
of 2.3 g/dL and 95 percent respectively.

All patients (100 percent) had met at least three of the four
hematologic and visceral therapeutic goals established for enzyme
replacement therapy.

These data also indicate continued improvement in bone mineral density
by DXA, with a mean T-score increase of 0.8 from baseline in the
lumbar spine.

“Eliglustat tartrate represents a new hope for Gaucher disease type 1
patients,” said Manisha Balwani, MD, MS, Department of Genetics and
Genomic Sciences, Mount Sinai School of Medicine. “The option of an oral
therapy offers convenience, expanded access to treatment and, most
important, an improvement in the quality of life for patients.
Eliglustat tartrate marks a potential paradigm shift in Gaucher
treatment.”

“The four-year data from our phase 2 eliglustat tartrate study show very
encouraging results, particularly the continued improvements observed in
markers of bone disease," said Genzyme’s Head of Rare Diseases, Rogerio
Vivaldi, MD. “The efficacy of eliglustat tartrate, combined with its
safety profile, demonstrate its potential to transform the treatment
experience for the Gaucher community. We look forward to continuing our
momentum in the phase 3 program.”

In the phase 2 study, the most common adverse events reported in greater
than two patients through four years of treatment included viral
infections (six patients), urinary tract and upper respiratory tract
infections (four patients each), and nasopharyngitis, sinusitis,
arthralgia, pain in extremity, headache, increased blood pressure,
abnormal nerve conduction study, abdominal pain, and diarrhea (three
patients each). Ten drug-related adverse events, including one serious
event, were reported in eight patients. All related events were mild in
severity.

Genzyme has also fully enrolled all three phase 3 trials for the oral
therapy. Combined, these trials represent the largest clinical program
ever focused on Gaucher disease, with participating sites in over 30
countries. In total, more than 350 patients are enrolled in the phase 3
studies.

The first phase 3 trial, ENCORE, is a randomized, open-label study for
adult patients with Gaucher disease type 1, designed to compare
eliglustat tartrate to Cerezyme. Adult patients who previously received
enzyme replacement therapy for at least three years and have reached
their therapeutic goals are enrolled in this trial. The second trial,
ENGAGE, is a randomized, double-blind, placebo-controlled study for
patients with Gaucher disease type 1 who were untreated or had not been
on treatment for at least nine months prior to study entry. Data from
these pivotal registration studies are expected in the first half of
2013. A third trial, known as EDGE, compares once-daily dosing of
eliglustat tartrate with twice-daily dosing.

About Gaucher disease

Gaucher disease is an inherited condition affecting fewer than 10,000
people worldwide. People with Gaucher disease do not have enough of an
enzyme, β-glucosidase (glucocerebrosidase) that breaks down a certain
type of fat molecule. As a result, lipid engorged cells (called Gaucher
cells) amass in different parts of the body, primarily the spleen, liver
and bone marrow. Accumulation of Gaucher cells may cause spleen and
liver enlargement, anemia, excessive bleeding and bruising, bone disease
and a number of other signs and symptoms. The most common form of
Gaucher disease, type 1, generally does not affect the brain.

About eliglustat tartrate

Eliglustat tartrate, a novel glucosylceramide analog given orally, is
designed to partially inhibit the enzyme glucosylceramide synthase,
which results in reduced production of glucosylceramide.
Glucosylceramide is the substance that builds up in the cells and
tissues of people with Gaucher disease. In preclinical studies, the
molecule, developed with James A. Shayman, MD, from the University of
Michigan, has shown high potency and specificity. Based on its mechanism
of action, which is independent of genotype, eliglustat tartrate may be
a potential therapy for all patients with Gaucher disease type 1.
Initiation of the phase 2 and 3 studies of eliglustat tartrate in
Gaucher disease followed an extensive pre-clinical research effort and a
phase 1 program. Eliglustat tartrate was well-tolerated through 4 years
in the phase 2 study and continues to have a safety profile that
supports clinical investigation in phase 3 studies.

Cerezyme important safety information

Approximately 15 percent of patients have developed IgG antibodies to
the infused enzyme. These patients have a higher risk of
hypersensitivity reaction. Therefore periodic monitoring is suggested;
caution should be exercised in patients with antibodies or prior
symptoms of hypersensitivity. Symptoms suggestive of hypersensitivity
occurred in 6.6 percent of patients, and include anaphylactoid reaction,
pruritus, flushing, urticaria, angioedema, chest discomfort, dyspnea,
coughing, cyanosis and hypotension. Reactions related to Cerezyme
administration have been reported in less than 15 percent of patients.
Each of the following events occurred in less than two percent of the
total patient population. Reported adverse events include nausea,
vomiting, abdominal pain, diarrhea, rash, fatigue, headache, fever,
dizziness, chills, backache and tachycardia. Adverse events associated
with the route of administration include discomfort, pruritus, burning,
swelling or sterile abscess at the site of venipuncture. For full
prescribing information, please visit www.genzyme.com.

About Genzyme, a Sanofi Company

Genzyme has pioneered the development and delivery of transformative
therapies for patients affected by rare and debilitating diseases for
over 30 years. We accomplish our goals through world-class research and
with the compassion and commitment of our employees. With a focus on
rare diseases and multiple sclerosis, we are dedicated to making a
positive impact on the lives of the patients and families we serve. That
goal guides and inspires us every day. Genzyme’s portfolio of
transformative therapies, which are marketed in countries around the
world, represents groundbreaking and life-saving advances in medicine.
As a Sanofi company, Genzyme benefits from the reach and resources of
one of the world’s largest pharmaceutical companies, with a shared
commitment to improving the lives of patients. Learn more at www.genzyme.com.

Genzyme® and Cerezyme® are registered trademarks
of Genzyme Corporation. All rights reserved.

Although Dr. Balwani is a member of the Gaucher Registry advisory board,
she receives no financial compensation for this service. Dr. Balwani
received a one-time honorarium for her service at a scientific meeting
sponsored by Genzyme.

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